In the fields of elevators, automobiles, construction machinery and the like, an embedded control device which controls a control target with so-called embedded software is used. As advantages of embedded software, the ability to realize more flexible and advanced control than in a conventional method using on a mechanical system or electric circuit and the ability to develop many variation products by partial change in the software can be mentioned.
Such an embedded control device, for example, an elevator control device employs a so-called data-driven computation model in which a task is started on a predetermined cycle or according to an interrupt and control variables are updated based on an input from a destination floor designation button or a sensor such as door safety sensor, thus controlling an actuator such as door open/close motor or cage drive motor.
Meanwhile, there is a problem that as control processing which is required of the embedded control device becomes complicated year by year, the dependence relation between control variables becomes more complicated, making the software difficult to understand.
For example, in the case of control software updated with several thousand variables, if the operation method of a variable at one site is changed, it is essential to specify variables which are influenced by the change and thus verify the software.
Patent Document 1, mentioned below, discloses an example of a business-use software maintenance supporting device which makes analysis based on the data type of variables. This software maintenance supporting device divides the type of data into domains such as “date data” based on variable definitions and a determination text on the source code, analyzes the relation between the domains, and displays the software structure.
Patent Document 2, mentioned below, discloses an example of a software maintenance supporting device which highlights a processing content related to a variable which the user focuses on. The processing content of a specific function is illustrated and a processing block related to the variable which the user focuses on is clarified in cooperation by a technique such as bold-line display.